This invention relates to centrifugal blowers and to chemical reactors incorporating same.
Centrifugal blowers, or centrifugal fans, are a well known type of device for providing a flow or movement of a gaseous medium. A common type of centrifugal blower includes a housing having an axially directed gas inlet and a radially directed gas outlet, an impeller disposed within the housing for drawing gas at a first pressure into the inlet and expelling gas at a second higher pressure through the outlet and a motor for driving, i.e., spinning, the impeller. Variations of this general type of centrifugal blower are disclosed in, e.g., U.S. Pat. Nos. 4,917,572; 5,839,879; 6,877,954; 7,061,758; 7,351,031; 7,887,290; 7,891,942, and, U.S. 2006/0051203, the entire contents of which are incorporated by reference herein.
Centrifugal blowers of the general type referred to above have been disclosed as components of gas phase chemical reactors of various kinds including reformers (devices for converting liquid and gaseous reformable fuels to hydrogen-rich products), fuel cells (devices for the electrochemical conversion of electrochemically oxidizable fuels such as the hydrogen-rich product of a reformer to electricity and potentially useful recoverable heat), integrated reformer-fuel cell systems, fluidized bed reactors for gas phase olefin polymerization, catalytic combustors, gas-liquid circulating gas hydrate reactors, gas phase oxidation reactors and water-gas shift reactors where the blowers perform gas-driving operations essential to their operation. For example, in the case of a partial oxidation reformer, a centrifugal blower is commonly employed to provide a flow of oxygen-containing gas such as air to a mixing zone where the gas combines with a gaseous or vaporized liquid reformable fuel to form a gaseous partial oxidation reaction mixture. The same centrifugal blower also drives the gaseous reaction mixture into a gas phase partial oxidation reaction zone where the mixture undergoes conversion to a hydrogen-rich reformate, and the resulting product reformate therefrom.
DeWald et al. us 2012/0328969, the entire contents of which are incorporated by reference herein, describes a blower system comprising a series of interconnected, independently controllable centrifugal blower units in which gaseous discharge from the radial outlet of one blower in the series is introduced into the axial inlet of another blower unit in the series via a duct connecting both blower units.
The centrifugal blower system of US 2012/0328969 possesses several advantages over conventional and otherwise known single centrifugal blowers such as those mentioned above, particularly in the ability to make rapid and accurate gas flow adjustments in response to frequently changing gas flow requirements for the gas phase chemical reactor to which the blower is connected, e.g., as in the reformers and integrated reformer and fuel cell assemblies disclosed in Finnerty et al. U.S. patent application Ser. Nos. 14/533,702 and 14/533,803, both filed Nov. 5, 2014, and Ser. Nos. 14/534,345 and 14/534,409, both filed Nov. 6, 2014, the entire contents of which are incorporated by reference herein.
In known and conventional centrifugal blowers that are utilized for driving gaseous reactant mixtures into, within and from the gas phase reaction zone of a chemical reactor, the blower provides a flow of first reactant gas which combines with a flow of second reactant gas external to the blower to provide a gaseous reaction mixture which is then introduced to the reaction zone. In order to mix the first and second gases more thoroughly than could be expected to occur simply through turbulent mixing that takes place upon merger of the two gas streams, a mixing device such as a static or power-driven mixer may be utilized to accomplish this objective. However, the degree of mixing that can be achieved with such a mixing device, while an improvement over mere turbulent mixing, may still be well short of optimum (especially in the case of a static mixer), introduces further structural complexity (especially in the case of a power-driven mixer) and in any case may cause an undesirable level of back pressure.
There is thus a need for a centrifugal blower or centrifugal blower system for driving gaseous mixtures that avoids the use of an external mixing device to provide a more uniform mixture of two or more gases than can be achieved by turbulent mixing alone.